[R-390] AVC voltages?

[Flowertime01 at wmconnect.com]

Ed,

>From your statement.
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Just to clarify- the radio works fine, and doesn't overload on strong  
signals.  The AVC seems to switch normally, and the meter zeros OK.   However, the 
meter pins with a signal input that should only read 80 dB.  I  haven't checked 
the linearity, but I think it reads high for most of the  range.

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You could just have a problem with the meter set resistor R523. This is a 100 
ohm resistor across a 22 ohm resistor. This item has been a problem for 
setting the carrier level meter since day one. Time has not improved the 
performance of the circuit. The resistor gets dirty and hard to adjust. At low level low 
current the meter lays at zero or near zero OK. But on a strong signal the 
circuit current changes and in the dirty pot the conduction changes a whole 
bunch and the meter reads high.

Several fixes have been tried and are in use. A ten turn pot is one fix. Just 
clean up the one you have is another fix. Add a few ohms in series with the 
pot to move the adjustment spot off the worn spot is another fix. Then you can 
replace the current pot.

As the meter circuit is not calibrated to any known standard, you can just 
live with it.

One way to set the pot is to set it to mid scale with a good signal coming in.
This is easier than trying to get the needle to lay at zero with no signal.

Watch for some more post from others. Their are semantics on the WWW. One of 
the
fellows did a wonderful job of reading almost any point we could think of and 
annotating the schematic with the voltages. That info is out there. I do not 
have the address at hand or I would post it for you.

If the receiver is working OK I would think a problem in the meter circuit.

Roger AI4NI